Fibers, fabrics and preform manufacturing

Fibers carry structural loads and provide stiffness and strength to the composite part. Short fibers and natural fibers (such as hemp, flax and jute) are 

A mat is a ply of chopped (short or long) yarns that are held together by a binder or stitches. A/ahnc is a ply of continuous yarns that are manufactured 

The major advantages of mats (compared to fabrics) are as follows (1) high porosity and thus permeability to resin flow (2) easy to handle (i.e., cut and place in the mold cavity) and (3) inexpensive. Their major disadvantages are as follows (1) low strength and stiffness and (2) low fiber volume fraction even at high compaction pressures due to non-structured plies. 

The common measure of a ply s density is its areal density (also known as superficial density). For example, a ply with 450 g/m superficial density weighs 450 g/m.  

8 (a)-(d) Common fiber mats and fabrics used in LCM. (Source Adapted from reference 5.)The bottom row is a zoomed version at 10 mm X 10 mm scale. 

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